CN106982076A - A kind of antenna fast matching method - Google Patents

Abstract

The present invention relates to wireless communication technology, a kind of antenna fast matching method, including step S1 S4, step S1 are specifically disclosed, inductance Lant amounts, loss resistance Rant values and the parasitic capacitance Cant values of antenna equivalent circuit is measured；Step S2, adjusts the antenna figure of merit Q values of the antenna circuit, and calculates the series resistance RQ values and the normalized impedance of antenna circuit of the adjustment Q values of the antenna circuitValue；Step S3, calculates the conjugation normalized impedance of low-pass filter circuit equivalent circuitStep S4, using Smith chart to obtained by calculatingWithCarry out conjugate impedance match.The present invention passes through Smith chart and corresponding matching primitives flow processing antenna circuit test process, test process is set not need Network Analyzer, it only can just complete to match work using a LCR electronic tester, so as to saving machine cost, make matching work more rapidly, it is terse, directly perceived, understandable.

Description

A kind of antenna fast matching method

Technical field

The present invention relates to wireless communication technology, and in particular to a kind of antenna fast matching method.

Background technology

Radio frequency identification (Radio Frequency Identification, RFID), is a kind of contactless automatic knowledge Other technology, carries out noncontact bidirectional data communication by wireless radio frequency mode, target is recognized and related data is obtained, and has Have the advantages that cost is low, positioning precision is high.Antenna is the important component of RFID system, is govern in numerous scenes The development of RFID technique, so the research and design for RFID antenna are very urgent.13.56MHz wireless smart card application is Through quite varied, such as bus IC card, China second-generation identity card etc. are applied, it then follows agreement have ISO/IEC 14443-Type A and ISO/IEC 14443-Type B.Existing 13.56MHz Card Readers chip would generally provide reference circuit, matching element value, then Antenna match value is gone out by theoretical formula method, but the calculating process of this method is complicated, not directly perceived, influences design efficiency.

The content of the invention

In view of this, it is necessary to for it is above-mentioned the problem of there is provided a kind of antenna fast matching method.

To achieve the above object, the present invention takes following technical scheme：

A kind of 13.56MHz antennas universal design circuit includes low-pass filter circuit, match circuit, antenna circuit；

The low-pass filter circuit is used for the high frequency spurs for filtering out radio frequency chip output；

The match circuit includes shunt capacitance C1 and series capacitance C2, and match circuit is used for, and shunt capacitance C1 is used to filter The impedance matching of wave circuit and antenna circuit, series capacitance C2 is used for the impedance matching of filter circuit and antenna circuit；

The antenna circuit is used to launch 13.56MHz carrier waves.

A kind of antenna fast matching method, comprises the following steps：

Step S1, measures inductance Lant amounts, loss resistance Rant values and the parasitic capacitance Cant values of antenna equivalent circuit；

The antenna equivalent circuit is the antenna equivalent circuit of antenna circuit, is antiresonant circuit；

Step S2, adjusts the antenna figure of merit Q values of the antenna circuit, and calculates the adjustment of the antenna circuit The series resistance RQ values and the normalized impedance of antenna circuit of Q valuesValue；

Induction reactance that the antenna figure of merit Q values are presented when being worked by inductor under the alternating voltage of a certain frequency with The ratio between its equivalent loss resistance, the Q values of inductor are higher, and its loss is smaller, and efficiency is higher, but passband is narrower simultaneously；

Q value of the series resistance RQ values of the adjustment Q values for adjusting antenna, changes its passband；

The normalized impedance of the antenna circuitIt is worth for impedance matching；

Step S3, calculates the conjugation normalized impedance of low-pass filter circuit equivalent circuit

The low-pass filter circuit equivalent circuit is antiresonant circuit circuit；

The conjugation normalized impedanceFor impedance matching；

Step S4, using Smith chart to obtained by calculatingWithConjugate impedance match is carried out, for determining match circuit Component value；

The match circuit is used for the impedance matching of low-pass filter circuit and antenna circuit.

Further, the step S1 comprises the following steps：

Step S11, the antenna circuit in 13.56MHz antenna universal design circuits cooks up antenna equivalent circuit, institute Stating antenna equivalent circuit includes inductance Lant, loss resistance Rant, parasitic capacitance Cant, the inductance Lant and loss resistance Rant is connected in series, and parasitic capacitance Cant is connected in the two ends of inductance Lant and loss resistance Rant series circuit in parallel；

Step S12, inductance Lant amounts, loss resistance Rant values and parasitic capacitance are measured using LCR electronic testers Cant values.

Further, the step S2 comprises the following steps：

Step S21, adjusts the effective factor Q values of antenna circuit, and according to formulaCalculate Adjust the series resistance RQ values of Q values；

The formulaIn ω=2 π f, f be 13.56MHz, Q is 35；

Step S22, according to formulaCalculate the normalized impedance of antenna circuitValue；

The formulaR_aIt is worth for real part, R_aThe calculation formula of value is：

The formulaX_aIt is worth for imaginary part, X_aThe calculation formula of value is：

Wherein ω=2 π f, f are 13.56MHz.

Further, the step S3 comprises the following steps：

Step S31, low-pass filter circuit is cooked up according to the low-pass filter circuit of 13.56MHz antenna universal design circuits Equivalent circuit, the low-pass filter circuit equivalent circuit includes filter inductance Lo, filter resistance Rmatch, filter capacitor Co, institute State inductance Lo and filter resistance Rmatch to be connected in series, filter capacitor Co is connected in filter inductance Lo and filter resistance in parallel The two ends of Rmatch series circuit；

Step S32, according to formulaCalculateValue；

The formulaR_fIt is worth for real part, R_fThe calculation formula of value is：

The formulaX_fIt is worth for real part, X_fThe calculation formula of value is：

The R_fValue and X_fω in the calculation formula of value=2 π f, f are 13.56MHz, and L0 is 1uH, and C0 is 130pF, Rmatch is 50 Ω；

The conjugation normalized impedanceValue is according to formulaCalculate gained.

Further, the step S4 comprises the following steps：

Step S41, marks the normalized impedance of antenna circuit on Smith chartObtainMark point, and mark The conjugation normalized impedance of low-pass filter circuitObtainMark point；

Step S42,First the conductance such as edge circle is moved mark point, then is made by adjusting shunt capacitance C1 valuesMark point falls Waiting on resistance circle where mark point；

It is described to wait resistance circle to wait resistance circle involved by Smith chart；

Step S43,The resistance circle such as mark point edge is moved, then is made by adjusting series capacitance C2 valuesMark point with Mark point is overlapped；

Step S44, determines the shunt capacitance C1 values of the match circuit in 13.56MHz antenna universal design circuits and connects Electric capacity C2 values.

Beneficial effects of the present invention are：

The present invention makes to test by Smith chart and corresponding matching primitives flow processing antenna circuit test process Journey does not need Network Analyzer, only just can complete matching work using LCR electronic tester, thus save machine into This, make matching work more rapidly, it is terse, directly perceived, understandable.

Brief description of the drawings

Fig. 1 is a kind of flow chart of antenna fast matching method of the present invention；

Fig. 2 is a kind of circuit diagram of 13.56MHz antennas universal design circuit of the present invention；

Fig. 3 is the circuit theory diagrams of the antenna equivalent circuit of the present invention；

Fig. 4 is the circuit theory diagrams of the low-pass filter circuit equivalent circuit of the present invention；

Fig. 5 is normalized impedance of the inventionWith conjugation normalized impedanceIn the emulation schematic diagram of Smith chart.

Embodiment

To make the object, technical solutions and advantages of the present invention clearer, below in conjunction with the embodiment of the present invention, to this hair Bright technical scheme is made further clearly and completely to describe.It should be noted that described embodiment is only the present invention one Section Example, rather than whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art are not doing Go out the every other embodiment obtained under the premise of creative work, belong to the scope of protection of the invention.

Embodiment

As shown in Fig. 2 a kind of 13.56MHz antennas universal design circuit includes low-pass filter circuit, match circuit, antenna Circuit.

As shown in figure 1, a kind of antenna fast matching method, comprises the following steps：

Step S1, measures inductance Lant amounts, loss resistance Rant values and the parasitic capacitance Cant values of antenna equivalent circuit；

Step S2, adjusts the antenna figure of merit Q values of the antenna circuit, and calculates the adjustment of the antenna circuit The series resistance RQ values and the normalized impedance of antenna circuit of Q valuesValue；

Step S3, calculates the conjugation normalized impedance of low-pass filter circuit equivalent circuit

Step S4, using Smith chart to obtained by calculatingWithConjugate impedance match is carried out, for determining match circuit Component value.

The step S1 comprises the following steps：

Step S11, as shown in figure 3, the antenna circuit in 13.56MHz antenna universal design circuits cooks up antenna Equivalent circuit, the antenna equivalent circuit includes inductance Lant, loss resistance Rant, parasitic capacitance Cant, the inductance Lant It is connected in series with loss resistance Rant, parasitic capacitance Cant is connected in inductance Lant and loss resistance Rant series circuit in parallel Two ends；

Step S12, inductance Lant amounts, loss resistance Rant values and parasitic capacitance are measured using LCR electronic testers Cant values；

The step S2 comprises the following steps：

Step S21, adjusts the effective factor Q values of antenna circuit, and according to formulaCalculate Adjust the series resistance RQ values of Q values；

The formulaIn ω=2 π f, f be 13.56MHz, Q is 35；

Step S22, according to formulaCalculate the normalized impedance of antenna circuitValue；

The formulaR_aIt is worth for real part, R_aThe calculation formula of value is：

The formulaX_aIt is worth for imaginary part, X_aThe calculation formula of value is：

Wherein ω=2 π f, f are 13.56MHz；

The step S3 comprises the following steps：

Step S31, as shown in figure 4, being cooked up according to the low-pass filter circuit of 13.56MHz antenna universal design circuits low Bandpass filter circuit equivalent circuit, the low-pass filter circuit equivalent circuit includes filter inductance Lo, filter resistance Rmatch, filtering Electric capacity Co, the inductance Lo and filter resistance Rmatch are connected in series, and filter capacitor Co is connected in filter inductance Lo and filter in parallel The two ends of ripple resistance Rmatch series circuit；

Step S32, according to formulaCalculateValue；

The formulaR_fIt is worth for real part, R_fThe calculation formula of value is：

The formulaX_fIt is worth for real part, X_fThe calculation formula of value is：

The R_fValue and X_fω in the calculation formula of value=2 π f, f are 13.56MHz, and L0 is 1uH, and C0 is 130pF, Rmatch is 50 Ω；

The conjugation normalized impedanceValue is according to formulaCalculate gained.

As shown in figure 5, the step S4 comprises the following steps：

Step S41, marks the normalized impedance of antenna circuit on Smith chartObtainMark point, and mark The conjugation normalized impedance of low-pass filter circuitObtainMark point；

Step S42,First the conductance such as edge circle is moved mark point, then is made by adjusting shunt capacitance C1 valuesMark point falls Waiting on resistance circle where mark point；

Step S43,The resistance circle such as mark point edge is moved, then is made by adjusting series capacitance C2 valuesMark point with Mark point is overlapped；

Step S44, determines the shunt capacitance C1 values of the match circuit in 13.56MHz antenna universal design circuits and connects Electric capacity C2 values.

Embodiment described above only expresses the several embodiments of the present invention, and it describes more specific and detailed, but simultaneously Therefore the limitation to the scope of the claims of the present invention can not be interpreted as.It should be pointed out that for one of ordinary skill in the art For, without departing from the inventive concept of the premise, various modifications and improvements can be made, these belong to the guarantor of the present invention Protect scope.Therefore, the protection domain of patent of the present invention should be determined by the appended claims.

Claims (5)

1. a kind of antenna fast matching method, it is characterised in that comprise the following steps：

Step S1, measures inductance Lant amounts, loss resistance Rant values and the parasitic capacitance Cant values of antenna equivalent circuit；

Step S2, adjusts the antenna figure of merit Q values of the antenna circuit, and calculates the adjustment Q values of the antenna circuit Series resistance RQ values and antenna circuit normalized impedanceValue；

Step S3, calculates the conjugation normalized impedance of low-pass filter circuit equivalent circuit

Step S4, using Smith chart to obtained by calculatingWithCarry out conjugate impedance match, the member for determining match circuit Part value.

2. a kind of antenna fast matching method according to claim 1, it is characterised in that the step S1 includes following step Suddenly：

Step S11, the antenna circuit in 13.56MHz antenna universal design circuits cooks up antenna equivalent circuit, the day Line equivalent circuit includes inductance Lant, loss resistance Rant, parasitic capacitance Cant, the inductance Lant and loss resistance Rant string Connection connection, parasitic capacitance Cant is connected in the two ends of inductance Lant and loss resistance Rant series circuit in parallel；

Step S12, inductance Lant amounts, loss resistance Rant values and parasitic capacitance Cant values are measured using LCR electronic testers.

3. a kind of antenna fast matching method according to claim 1, it is characterised in that the step S2 includes following step Suddenly：

Step S21, adjusts the effective factor Q values of antenna circuit, and according to formulaCalculate adjustment Q The series resistance RQ values of value；

The formulaIn ω=2 π f, f be 13.56MHz, Q is 35；

Step S22, according to formulaCalculate the normalized impedance of antenna circuitValue；

The formulaR_aIt is worth for real part, R_aThe calculation formula of value is：

The formulaX_aIt is worth for imaginary part, X_aThe calculation formula of value is：

Wherein ω=2 π f, f are 13.56MHz.

4. a kind of antenna fast matching method according to claim 1, it is characterised in that the step S3 includes following step Suddenly：

Step S31, cooks up low-pass filter circuit equivalent according to the low-pass filter circuit of 13.56MHz antenna universal design circuits Circuit, the low-pass filter circuit equivalent circuit includes filter inductance Lo, filter resistance Rmatch, filter capacitor Co, the electricity Sense Lo and filter resistance Rmatch is connected in series, and filter capacitor Co is connected in filter inductance Lo and filter resistance Rmatch's in parallel The two ends of series circuit；

Step S32, according to formulaCalculateValue；

The formulaR_fIt is worth for real part, R_fThe calculation formula of value is：

$R_f=\frac{\mathrm{Rmatch}}{{(1-\mathrm{\ω}\·L0\·C0)}^2-{(\mathrm{\ω}\·R0\·C0)}^2};$

The formulaX_fIt is worth for real part, X_fThe calculation formula of value is：

$X_f=2\mathrm{\ω}\frac{L0\·{(1-\mathrm{\ω}\·L0\·C0)}^2-\frac{\mathrm{Rmatch}}{2}\·C0}{{(1-{\mathrm{\ω}}^2\·L0\·C0)}^2+{(\mathrm{\ω}\·R0\·C0)}^2};$

The R_fValue and X_fω in the calculation formula of value=2 π f, f are 13.56MHz, and L0 is 1uH, and C0 is 130pF, and Rmatch is 50Ω；

The conjugation normalized impedanceValue is according to formulaCalculate gained.

5. a kind of antenna fast matching method according to claim 1, it is characterised in that the step S4 includes following step Suddenly：

Step S41, marks the normalized impedance of antenna circuit on Smith chartObtainMark point, and mark low pass The conjugation normalized impedance of filter circuitObtainMark point；

Step S42,First the conductance such as edge circle is moved mark point, then is made by adjusting shunt capacitance C1 valuesMark point falls Waiting on resistance circle where mark point；

Step S43,The resistance circle such as mark point edge is moved, then is made by adjusting series capacitance C2 valuesMark point withMark Point is overlapped；

Step S44, determines the shunt capacitance C1 values and series capacitance of the match circuit in 13.56MHz antenna universal design circuits C2 values.